Distribution of contents can be received through a network easily. When distribution of contents needs to be received with a fee, it is favorable to a contents user that the contents user can use contents as many as possible at low cost. In addition, it is preferable that procedures for distribution and use of contents are as easy as possible.
Also on the contents provider side, there is a demand that contents distribution procedures should be as easy as possible. Particularly in contents distribution service with a fee, there is a demand that accounting procedures are as few as possible and as easy as possible.
Patent Document 1 has disclosed a flat-rate contents distribution system. In this system, a user makes a contract with a contents provider for a flat-rate rental limit in advance. The contents provider distributes contents to the user in accordance with the contracted limit. Although the user can use distributed contents within the term of contract, the user can delete unnecessary contents within the term of contract when the unnecessary contents are included in the contents distributed at the flat rate. In this case, the contracted fee is discounted at an amount corresponding to the deleted contents when information concerned with the deleted contents is transmitted to a contract management center.
Since this system is basically a limited time rental service system, management burdens imposed on the user and the service provider are large. That is, the user has to always manage distributed contents while paying attention to necessity of the distributed contents to avoid wasteful payment. In addition, the user has to always make a new rental contract by troublesome procedures to receive distribution of new contents. On the other hand, the processing burden imposed on the service provider is also large because the service provider has to make management of a rental limit and a fee in accordance with each contract whenever a contents deletion process or a subscription to new contents distribution is made, and the service provider has to make an expiration period management process periodically.
Patent Document 2 has disclosed a system for use of contents with a fee, in which a paid fee is returned in accordance with a period of service. For use of this system, a user pays a provisional fee to a provider when contents with a fee are distributed. When unnecessary contents with a fee are deleted by the user after use of the contents, the provider returns a part of the provisional fee to the user. This returned amount of money is determined in accordance with the period of use of the contents. When a predetermined period has lapsed, the contents are regarded as “purchased” because the rental fee is equal to a purchase fee.
Also in this system, the burden imposed on the user is large because the user has to use distributed contents while always paying attention to the necessity of the distributed contents. The burden imposed on the service provider for management processing is also large because the service provider has to manage the periods of use periodically in accordance with contents. In addition, the burden for processing to return the paid fee is large.
In these systems, a contracted charge fee is discounted or a paid fee is returned when the user deletes distributed contents to disable the contents from use. It is therefore essential to system operation that information indicating deletion of contents (disabling contents from use) is highly reliable. Although Patent Documents 1 and 2 have described the fact that information indicating deletion of contents is transmitted, it is possible to make a false statement.
As an example of outputting of a signal for warranting deletion of contents stored in a storage device of a computer, a contents operation management apparatus has been described in Patent Document 3. In this apparatus, another computer having received a notice of deletion of contents checks a hard disk storing the contents and confirms deletion of the contents. It is however impossible to apply this technique to confirmation of deletion of contents in a user terminal through a network.    Patent Document 1: JP-A-2001-195464    Patent Document 2: JP-A-2001-325234    Patent Document 3: JP-A-2003-242037